When crops are harvested, much of the above-ground portion of the crop plants—termed the crop residue—is left above the soil surface. Traditional farming methods have included incorporating the crop residue into the soil before seeding the next crop. However, incorporating the crop residue leaves the soil surface bare and exposed to wind and water erosion. By contrast, reduced or eliminated tillage regimes leave all or a significant portion of the crop residue on the soil surface. The presence of the crop residue on the soil surface eliminates much of the erosion, which would otherwise occur if the soil was left exposed. In contrast to equipment used for traditional seeding, equipment for seeding into soils protected by reduced or eliminated tillage regimes must penetrate through the crop residue and into soils which are often more highly compacted than soils under traditional tillage regimes. Therefore, the equipment is usually heavier and made from components designed to withstand the additional stresses encountered when crop residue and more highly compacted soils are penetrated. Additionally, other materials such as fertilizers, herbicides, and pesticides must be placed adjacent the seed. In the case of fertilizers, the fertilizer materials must be placed adjacent the seed, but must be disposed sufficiently distant from the seed so that emerging seedlings are not damaged by high fertilizer concentrations in the soil water solution. While being sufficiently distant from the emerging seedlings, the fertilizer materials must also be sufficiently close to the emerging seedlings, so that non-injurious plant nutrient solution concentrations from the fertilizer materials are available to the crop plants shortly after germination and during emergence.
There is then a need for planters which effectively penetrate above-ground crop residues and more highly compacted soils during seeding operations. There is a particular need for planters, which effectively penetrate above-ground crop residues and more compacted soils and which also dispense additional materials at effective and safe locations in the soil profile.